FIG. 4.

Possible scenarios for temporal changes in host abundance as a consequence of viral lysis. In scenario 1, the abundance of the host population changes periodically, resembling predator-prey oscillations. Thus, viral lysis regulates numerically dominant populations (similar to negative frequency-dependent selection). In scenario 2, the host population is resistant to viral infection and thus can maintain high host abundance. This scenario is unlikely due to the transient nature of resistance and the associated costs of resistance. Scenario 3 depicts the case of a population that coevolves with its virus. The oscillations are due to a change in the population's sensitivity to the virus. In scenario 4, the sensitive host population is kept at a low abundance due to strong viral control.